Complete Denture Occlusion

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Complete Denture Occlusion
Rola M. Shadid, BDS, MSc
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• Occlusion
• the static relationship between the incising or
  masticating surfaces of the maxillary and
  mandibular teeth, or tooth analogs
• Articulation
• the contact relationship between the occlusal
  surfaces of teeth during function

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• Centric occlusion
• Eccentric occlusion
• Protrusive occlusion
• Lateral occlusion

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• Working side
• the side toward which the mandible moves in a
  lateral excursion
• Non working (balancing) side
• that side of the mandible that moves toward the
  median line in a lateral excursion.

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Occlusal Schemes For CD

• Balanced articulation
• Nonbalanced articulation (linear or monoplane
  articulation)
• Lingualized articulation
• Functionally generated occlusal scheme

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Balanced Occlusion/Articulation

• Bilateral simultaneous contact betw. anterior
  posterior teeth during all centric and eccentric
  positions
• There should be no interferences during movement
  from centric position to eccentric positions
• The movements should be in harmony with TMJ
  neuromuscular control

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Advantages of Balanced Occlusion

• To improve stability retention
• To decrease soreness resorption of residual
  ridge
• To improve oral comfort of the patient

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Mechanics Of Balanced Occlusion

• Christensens phenomenon

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• How Could You Achieve Balanced Occlusion In CD?

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Factors That Affect Occlusal Balance
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Factors Affecting Balanced Occlusion (Hanaus
Quint)

• 1. Condylar Guidance
• 2.  Incisal Guidance
• 3.  Plane of occlusion
• Cuspal inclination
• Compensating curve.

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Condylar Guidance

• Mandibular guidance
• generated by the condyle and articular disc
  traversing the contour of the glenoid fossae
• The posterior determinent of mandibular movement

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Condylar Guidance Angle

• The angle formed by an imaginary horizontal line
  at the superior head of the condyle and the path
  that the condyle will pass through during
  function
• Varies from individual to individual because of
  anatomical differences

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Incisal Guidance

• Its the influence of the contacting surfaces of
  the mandibular maxillary anterior teeth on
  mandibular movement

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Incisal Guidance Angle

• The angle formed by the intersection of the plane
  of occlusion and a line within the sagittal plane
  determined by the incisal edges of the maxillary
• and mandibular central incisors when the teeth
  are in maximum intercuspation

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Incisal Guidance Angle

• This angle varies directly with the vertical
  overbite and inversely with the horizontal
  overjet
• This angle is set to 10 in CD and not exceeding
  20

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Incisal Guidance
? Incisal Guidance Angle by ? horizontal overlap
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Incisal Guidance

• For CD, the incisal guidance should be as shallow
  as esthetics and phonetics will permit when
  arrangement of anterior teeth to reduce
  protrusive displacing forces

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Incisal Guidance

• ? Incisal Guidance Angle by either
• ? horizontal overlap
• ? vertical overlap

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If Increased Incisal Guidance Angle For CD?

• During protrusion
• Upper denture drops at the back
• Lower denture slides backward

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Plane Of Occlusion

• Its inclination can be altered slightly
• It is not as important as other factors

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Cusp Height Angulation

• It is the smooth gliding of the cusp tips along
  the cusp inclines of the opposing teeth to
  provide balanced articulation

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Cusp Height Angulation

• Anatomic teeth are easier to balance than
  nonanatomic teeth
• Cuspal inclines should not be too steep as it can
  increase lateral forces
• It is possible to decrease cuspal height by using
  compensating curves

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Compensating Curves

• Artificial curves introduced into complete
  denture occlusion to achieve balanced occlusion
• Are among the most important determinents of
  occlusal balance

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Compensating Curves

• The anteroposterior curving (in the median
  plane) and the mediolateral curving (in the
  frontal plane) within the alignment of the
  occluding surfaces and incisal edges of
  artificial teeth that is used to develop balanced
  occlusion

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The Curvatures In Natural Dentition

• Curve of Spee
• An arc of a circle 65mm to 70mm radius that
  touches the tips of all the mandibular teeth when
  the skull is viewed laterally when continued it
  touches the anterior surface of the condyles

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The Curvatures In Natural Dentition

• Curve Of Monson
• A proposed ideal curve of occlusion in which each
  cusp and incisal edge touches or conforms to a
  segment of the surface of a sphere 4 inches
  (102mm) in radius with its centre in the region
  of the glabella.

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Compensating Curves

• Anteroposterior curve
• Mediolateral curve

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Compensating Curves

• The steepness of the curve necessary to achieve
  balance is the result of guiding influence of
  angle of condylar guidance and angle of incisal
  guidance
• It is functionally and mechanically advantageous
  to keep compensating curve as modest as possible
  ? This is accomplished by setting as shallow an
  incisal guidance as phonetics, esthetics permit

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Theilmanns Formula

• IGxCG CHxOPxCC

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According To The Formula

• To achieve balanced occlusion For high condylar
  guidance we need to have high compensating curve,
  occlusal plane and cuspal height.
• To achieve balanced occlusion For high incisal
  guidance we need to have high compensating curve,
  occlusal plane and cuspal height.

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According To The Formula

• To achieve balanced occlusion, the steeper the
  condylar guidance, the greater the cusp height
  toward the posterior or the steeper the
  compensating curves

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According To The Formula

• To achieve balanced occlusion, the steeper the
  compensating curves, the less the cusp height
  toward the posterior

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Question

• Q) Suppose that the incisal guidance is set and
  the condylar guidance is steeper than your chosen
  20 degree teeth. To obtain balanced occlusion in
  your complete denture, what should you do?
• steepen the compensating curves in both sagittal
  and frontal planes
• steepen the compensating curves in only sagittal
  but not frontal plane
• decrease the inclination of occlusal plane
• decrease the steepness of compensating curves in
  both sagittal and frontal planes
• steepen the condylar guidance
• none of the above

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Occlusal Schemes For CD
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Philosophies of Denture Occlusion

• Many philosophies of arranging denture occlusion
• No definitive scientific studies prove one
  occlusal scheme clearly superior

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Occlusal Schemes

• Balanced articulation
• Nonbalanced articulation (linear or monoplane
  articulation)
• Lingualized articulation
• Functionally generated occlusal scheme

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Lingualized Occlusion
Max. lingual cusps contact central
fossae/marginal ridge 1mm space between buccal
cusps
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Lingualized Occlusion

• Lingualized occlusion is a type of bilaterally
  balanced occlusal schemes
• Anatomic teeth are used in the maxilla opposing
  a flat-cusped, or shallow cusped mandibular tooth.

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Lingualized Occlusion

• Forces directed toward lingual side
• Maxillary lingual cusps articulate with the
  mandibular central fossae
• Elimination of contacts on the buccal cusps in
  both centric and eccentric
• The aim is to provide greater masticating
  efficiency and the elimination of lateral
  interferences

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Lingualized Occlusion

• Maxillary anatomic (33)
• Mandibular Teeth
• Steep Condylar Guidance
• Shallow cusped (Anatoline)
• Shallow Condylar Guidance
• Non-anatomic (Portrait 0)

Lingualized (lingual contact)
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Lingualized Occlusion
Verify centric No max. buccal cusp contacts in
Centric Lateral excursions
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Contraindications Of Balanced Occlusion
Lingualized Occlusion

• Extreme cases of the following
• Difficulty in obtaining repeatable centric
  record (incoordination, jaw malrelations)
• Severe ridge resorption (lateral forces displace
  the denture) may more easily be handled with a
  monoplane scheme

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Monoplane Articulation (Neutrocentric Concept)

• Cuspless teeth (0) on a flat plane with
  1.5-2.0 mm overjet
• No cusp to fossa relationship
• No anterior contacts in centric position

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Monoplane Articulation

• Eliminate cusps
• lateral forces reduced
• improves stability
• Simplifies tooth arrangement

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Monoplane Articulation

• No overbite (would cause tilting)
• Overjet of 2 mm is used to create an illusion of
  overbite

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Monoplane Articulation

• Excursions - may or may not contact on balancing
  sides
• Depends on condylar inclination and other aspects
  of the tooth arrangement

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Monoplane Articulation

• Anterior teeth make contact in excursions
• Modifications have been proposed to minimize the
  tilting potential
• Compensating curves

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Monoplane Occlusionwithout condylar influence
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Monoplane Occlusion
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Monoplane Articulation

• Advantages
• Technically easier to achieve
• Use when
• Difficulty obtaining repeatable centric records
  (muscle incoordination)
• Skeletal malocclusion (Class II, III)
• Severe residual ridge resorption
• Reduces horizontal forces

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Monoplane Articulation

• Disadvantages
• Poorer appearance
• Can be unstable if condylar guidance is steep
  (posterior teeth separate, leaving only the
  anteriors in contact)

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Monoplane Articulation

• Contraindications
• The patient has high expectations for improved
  appearance
• Very steep condylar guidance may make a monoplane
  scheme less stable, unless modifying ramps or
  compensating curves are used.

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When 1.5-2.0mm of overjet can be set, a
lingualized occlusion (left) can have overbite
set. Monplane occlusion (right) should normally
have no overbite set.